Method for calibrating the orientation of an acceleration sensor mounted on a vehicle

Abstract

The method relates to a method for calibrating the coordinate system of a multi-axis deceleration sensor in a railway vehicle, the method comprising the steps of: aligning the vertical axis of the sensor with the vertical axis of the vehicle (z Fahrzeug ) at low speeds, during the braking process of the rail vehicle (10) and at standstill, over time, measuring the longitudinal and lateral axes (x Sensor Or y Sensor ) along the longitudinal direction of the sensor (x Sensor ) and the horizontal (y Sensor ) and represents the effect of gravitational acceleration on the measured acceleration of the railway vehicle. o ), determining at least one resulting acceleration vector (a r The vertical axis (z ) of the sensor points in the longitudinal direction of the vehicle. Sensor At least one resulting acceleration vector (a r ) is obtained.

Description

Technical Field

[0001] The present invention relates to a method for calibrating the orientation of an acceleration sensor mounted on a vehicle, in particular to a method for calibrating the orientation of a coordinate system of a multi-axis acceleration sensor in a railway vehicle, an apparatus configured to carry out this method, and a computer program product configured to automatically carry out this method.

[0002] In recent vehicles, especially railway vehicles, deceleration adjustment is used to ensure economic, comfortable and safe braking. Such adjustment is described, for example, in patent documents, German Patent Application Publication No. 102015110053 or German Patent Application Publication No. 102011052545, and to adjust the deceleration, the actual deceleration signal of the vehicle in the longitudinal direction of the vehicle is required.

[0003] Such a signal can be obtained, for example, based on an acceleration sensor incorporated in a train. Here, when the track is inclined, the acceleration in the longitudinal direction of the vehicle may need to be corrected by the amount of the downhill force component in some cases. Here, the longitudinal acceleration of the vehicle can be detected by a uniaxial sensor accurately oriented in the longitudinal direction of the vehicle.

[0004] However, the installation of sensors that are accurately aligned requires a lot of effort, the positioning of the sensors is restricted, and it is not comfortable. Instead of uniaxial sensors, multi-axis acceleration sensors (especially 2-axis sensors or 3-axis sensors) can also be used. In particular, when using sensors with three or more axes, these sensors can be incorporated into the vehicle in an arbitrary orientation. Such sensors are integrated, for example, in a control device (brake control unit) that can be arranged in an arbitrary orientation within the vehicle.

[0005] However, multi-axis sensors have the drawback that they must first be calibrated to match the vehicle's coordinate system in order to accurately determine the acceleration in the longitudinal or lateral direction of the train. Such calibration is preferably carried out on a levelled track section that must not have a curve radius, track cant (lateral inclination of the track) or gradient. In this way, in the longitudinal or lateral acceleration of the vehicle, the longitudinal or lateral components of the sensor that occur based on the gravitational acceleration on a non-flat track and thus may mean calibration distortion can be excluded. Therefore, any actual, seemingly flat and straight route section where the curve radius, track cant and gradient or declivity cannot be excluded is not suitable for sensor calibration. Since the sensor can only be calibrated to match the longitudinal axis of the vehicle when the vehicle is moving dynamically, it is necessary that, to the extent possible, the levelled track section is significantly longer than the length of the vehicle.

[0006] Such track sections are rarely available in the actual route network, and transporting the vehicle to a calibrated track section and thus also the calibration itself involve a great deal of time, logistics costs and expenses.

[0007] Therefore, the object of the present invention is to provide a method for calibrating the orientation of the longitudinal axis and the lateral axis of an acceleration sensor mounted on a vehicle, and an apparatus belonging thereto, which make it possible to perform accurate calibration without using a levelled track section and thus reduce the cost and time consumption for calibration.

[0008] The above object is solved by the method, apparatus and computer program product described in the independent claims. Advantageous developments of the present invention are described in the respective dependent claims.

[0009] The vertical axis of the sensor is perpendicular to the lateral axis and the longitudinal axis of the sensor. Similarly, the lateral axis and the longitudinal axis of the sensor are perpendicular to each other. This is obvious from these names. That is, the three axes together form the coordinate system of the sensor, which is calibrated according to the coordinate system of the vehicle, which is also composed of three mutually perpendicular axes (longitudinal axis, lateral axis, vertical axis) based on the method of the present invention. The method of the present invention is composed of a plurality of steps.

[0010] In the first step (step (A)), the accelerations in the directions of the longitudinal axis and the lateral axis of the sensor (longitudinal or lateral) are measured over time during deceleration of the vehicle on an arbitrarily selected route section at low speed and further in the stopped state. From these acceleration profiles, an acceleration vector can be formed by obtaining the values of the accelerations in the longitudinal and lateral directions of the sensor at each same point in time. Therefore, the value of the acceleration vector represents the measured acceleration value of the vehicle at this point in time.

[0011] In the next step (step (B)), an offset vector corresponding to the acceleration vector measured in the stopped state is determined. That is, this includes the accelerations in the longitudinal and lateral directions of the sensor caused by the slope or the downward slope force based on the rise or fall of the line section where the vehicle exists in the stopped state. If this line section is exactly flat, the offset vector is 0 m / s 2 . That is, the offset vector represents the influence of the gravitational acceleration on the acceleration measured in the longitudinal or lateral direction of the sensor, and therefore occurs only when the line section where the vehicle exists is not flat.

[0012] Subsequently, in a further step (step (C)), at least one measured acceleration vector at the time of braking, i.e., while the vehicle is moving, is adjusted by subtracting the offset vector of the influence of the gravitational acceleration (downhill force) on the acceleration in the longitudinal or lateral direction of the sensor. Thus, the resulting acceleration vector from here corresponds to the measured longitudinal deceleration of the vehicle.

[0013] In a final step, the coordinate system of the sensor is transformed such that at least one resulting acceleration vector points in the longitudinal direction of the vehicle, i.e., in the direction of the longitudinal axis of the vehicle's coordinate system.

[0014] In an advantageous embodiment, to transform the coordinate system of the sensor to match the vehicle's coordinate system, the angle between the longitudinal axis of the sensor and at least one resulting acceleration vector is calculated in a plane spanning the longitudinal axis and the lateral axis of the sensor. Here, at least one resulting acceleration vector is the acceleration vector adjusted by the offset vector in the previous step. If multiple resulting acceleration vectors are obtained and an averaged resulting acceleration vector is obtained by averaging them, the angle between the longitudinal axis of the sensor and the averaged resulting acceleration vector is calculated in a plane spanning the longitudinal axis and the lateral axis of the sensor.

[0015] Finally, the coordinate system of the sensor is rotated by this calculated angle about the already calibrated vertical axis of the sensor. Thus, the longitudinal axis of the sensor coincides with the longitudinal axis of the vehicle, and the axis is calibrated accordingly. By definition, since the longitudinal axis is perpendicular to the lateral axis, this also ensures that the lateral axis of the sensor coincides with the lateral axis of the vehicle. This method can be carried out constantly during continuous operation or at intervals, and thus the calibration of the sensor can be updated constantly or at intervals.

[0016] In a further advantageous embodiment of the invention, in order to transform the coordinate system of the sensor (step (D)), a rotation matrix for the rotation of the coordinate system of the sensor about the vertical axis is determined. This rotation matrix is here composed of at least one unit vector to be determined of the resulting acceleration vector in the direction of the longitudinal axis and the transverse axis of the sensor.

[0017] In an advantageous embodiment of the invention, before the first step (A), i.e., before the recording of the acceleration of the vehicle in the longitudinal and transverse directions at low speed, the vertical axis of the sensor is calibrated to match the vertical axis of the vehicle. Here, the vertical axis of the sensor is perpendicular to both the transverse axis and the longitudinal axis of the sensor.

[0018] Even more advantageously, the calibration of the vertical axis of the sensor is carried out on a flattened measurement track and / or a calibrated measurement track and / or in the stationary state of the railway vehicle. Here, the flattened track section does not need to be longer than the part of the railway vehicle on which the sensor is mounted. Thus, such a calibration can already be carried out when the railway vehicle is completed. By means of this calibration on the flattened track section, it can be ensured that the sensor detects only the gravitational acceleration acting on the sensor in the vertical direction. In this way, the vertical axis of the sensor can be easily calibrated.

[0019] In an advantageous embodiment of the invention, at least one resulting acceleration vector determined in step (C) is within a calibration window. The calibration window is a time window with a defined start and end, and both the defined start and end are each shiftable in time in relation to the measured acceleration profile. Furthermore, the start and end of the calibration window may be determined, for example, by the parking jerk of the vehicle when stationary or based on defined speed values at which the window starts or ends.

[0020] All acceleration vectors used for calibration are located within the calibration window. Thus, intervals of the braking process that may cause calibration distortion, such as regions where the vehicle speed is too fast or too slow, can be excluded from calibration to improve the quality of the results.

[0021] In an advantageous embodiment of the invention, the acceleration history measured in step (A) is filtered to eliminate possible measurement noise or other measurement errors from the acceleration history and thus further improve the quality of the calibration results. Here, filtering by a low-pass filter that removes the high-frequency components of the measured acceleration history is particularly advantageous.

[0022] In a further advantageous embodiment, in step (C), a plurality of resulting acceleration vectors are determined. Next, these individually determined resulting acceleration vectors are averaged. Next, the coordinate system is transformed based on this averaged resulting acceleration vector, and as a result, this points in the longitudinal direction of the vehicle, i.e., the direction of the longitudinal axis of the vehicle. Such an embodiment has the advantage that a plurality of acceleration vectors are considered within the calibration window, whereby the inaccuracies of the measurements with individual acceleration vectors do not distort the result as strongly. Furthermore, in this way, possible slight differences in the slope (rise or track cant) of the track in the longitudinal or transverse direction can be compensated for between the calibration windows.

[0023] In a further advantageous embodiment of the invention, the offset vector is formed in step (B) by forming the average value of the various detected acceleration vectors. These acceleration vectors are composed of the longitudinal and transverse components of the sensor and are present within a defined offset window. The offset window represents the time window during which the vehicle is in a stationary state and may be defined, for example, based on the vehicle's stop jerk. In this way, the inaccuracies of the measurements during the stationary state of the vehicle can be reduced and an offset vector that is as accurate as possible can be determined.

[0024] In an advantageous embodiment of the invention, before the measurement value recording in step (A), at least one precondition is checked. These preconditions are, for example, that the speed of the vehicle exceeds a defined minimum speed and / or that the target deceleration applied by the vehicle's braking system exceeds a defined minimum target deceleration, for example 0.8 m / s 2 ². In this way, the probability that the measurement value recording causes inaccurate results can be reduced, and thus the quality of the calibration can be improved. If at least one of these conditions is not met, this calibration is declared invalid and aborted.

[0025] Furthermore, embodiments of the invention are advantageous in which, after the measurement value recording of the acceleration profile in step (A), certain secondary conditions are checked. For example, as a condition, it can be defined that the speed of the vehicle at the time of measuring the acceleration profile exceeds a defined minimum speed.

[0026] Further conditions can be that each of the measured acceleration vectors has a value exceeding a minimum acceleration, for example 0.6 m / s 2 ², or that braking is carried out until the vehicle is in a stopped state.

[0027] In order to ensure that the offset vector measured in the stopped state is realistic, it can further be defined as a condition that the measured offset vector must not deviate from the acceleration due to gravity by more than a defined value.

[0028] As long as they do not contradict each other, various conditions can be arbitrarily combined with each other and adapted as necessary. Such embodiments have the advantage that calibrations based on unrealistic measurements can be declared invalid and excluded by the set conditions.

[0029] In a further advantageous embodiment of the invention, the subsequent steps after step (D) are continued only if the values of the two resulting acceleration vectors and / or their angles determined in step (D) differ by no more than a defined value, for example 3°. Such secondary conditions can, also in this case, identify invalid or inaccurate calibrations and exclude them.

[0030] In an alternative embodiment, the measurement recording is carried out along the longitudinal and transverse axes of the sensor according to step (A) when accelerating from a standstill. Subsequently, the evaluation of the recorded measurement values is carried out in the same way as the procedure described above.

[0031] In an advantageous embodiment of the invention, furthermore, this method is carried out constantly during normal operation of the vehicle or at defined intervals. This has the advantage that the coordinate system of the sensor is constantly realigned, thereby enabling the vehicle acceleration to be determined accurately at all times.

[0032] The device of the invention has an operating unit configured to carry out the method according to claim 1, which is operated by an operator and configured to receive commands from the operator. The device further has a storage unit configured to store data collected during the implementation of the method, a computing unit configured to process data collected during the implementation of the method, and a data interface configured to receive data detected by the sensor and also to output data determined and / or processed by the device to the operator or to another system.

[0033] The computer program product of the invention is configured to automatically execute the steps according to claim 1 and thus to ensure automatic calibration of the sensor.

[0034] In the following, the invention will be explained in more detail based on embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3a

Figure 3b

Figure 4

Figure 5

[0036] FIG. 1 shows a railway vehicle (10) on a track (20), and the railway vehicle (10) has an acceleration sensor (30) incorporated therein in an arbitrary orientation. Here, the coordinate system (x Sensor , y Sensor , z Sensor ) of the sensor is not aligned with the coordinate system (x Fahrzeug , y Fahrzeug , z Fahrzeug ) of the railway vehicle (10). In order to detect the acceleration in the longitudinal direction (x Fahrzeug ) or the lateral direction (y Fahrzeug ) of the vehicle (10) using the acceleration sensor (30), first, the coordinate system of the sensor (30) must be calibrated to match the coordinate system of the vehicle. This means that the corresponding coordinate axes of each coordinate system need to be oriented parallel to each other. For this purpose, the x-axis (x Sensor ) of the sensor should correspond to the x-axis (x Fahrzeug ) of the vehicle, that is, the longitudinal axis of the vehicle, and the y-axis (ySensor ) should correspond to the y-axis (y Fahrzeug ) of the vehicle, i.e., the lateral axis of the vehicle, and the z-axis (z Sensor ) of the sensor should correspond to the z-axis (z Fahrzeug ) of the vehicle, i.e., the vertical axis of the vehicle.

[0037] For this purpose, first, the vertical axis z of the sensor Sensor is calibrated to match the vertical axis z of the vehicle Fahrzeug . Here, the part of the vehicle where the acceleration sensor is installed has no truck cant or inclination and is thus placed on a completely flat and leveled track section. Here, in this state, the acceleration detected by the acceleration sensor corresponds to the known gravitational acceleration acting only in the vertical direction of the vehicle. Therefore, the coordinate system of the sensor can be aligned such that the vertical axis of the sensor is oriented parallel to the vertical axis of the vehicle.

[0038] Next, the remaining two axes x Sensor and y Sensor of the sensor are calibrated to match the longitudinal axis or lateral axis (x Fahrzeug or y Fahrzeug ) of the vehicle. For this purpose, during operation or during the start-up driving of the vehicle, the acceleration profile of the sensor in the x-direction or y-direction is detected and evaluated during the braking process in a low-speed range and in the subsequent stopped state. This evaluation in a small speed range can reduce the influence of the curve radius of the track that may extend. Before the calibration is successful, the sensor signal is not used in the system.

[0039] Figure 2 shows the three coordinate directions (x Sensor , y Sensor , z Sensor) and the associated speed curve over time. The vehicle speed decreases linearly, while the acceleration curve remains approximately constant except for the start of braking and when the vehicle comes to a standstill. These curves therefore represent the braking process of the vehicle with approximately constant deceleration. Here, the deceleration in the x-direction of the sensor is significantly greater than the deceleration in the y-direction. To enable the data to be processed more appropriately, it is filtered using a low-pass filter. This low-pass filter removes high-frequency components of the curve, which may be caused by measurement noise, for example.

[0040] The evaluation begins with defining a calibration window and an offset window. The start and end of the two windows can be defined, for example, via the vehicle's start-of-travel jerk or stopping jerk. The duration of the time window can additionally be adjusted depending on the measurement results or the track conditions. The calibration window can be defined such that the start of the calibration window is defined by a defined period, for example, 5 seconds, before the detected stopping jerk. The end of the calibration window is then determined by a second defined, smaller period, for example, 1 second, before the stopping jerk. The offset window can also be defined using a similar procedure.

[0041] Another way to define the calibration window is to define a predetermined threshold for the vehicle speed at which the calibration window begins or ends. For example, it may be defined that the window begins when the vehicle is traveling at a speed of 2 m / s and ends when the vehicle is traveling at a speed of only 0.5 m / s.

[0042] For the calibration of the sensor, only the progression within the two windows is used. Each acceleration vector, consisting of an x-component and a y-component at the same time, is formed in both the calibration window and the offset window. For this purpose, Fig. 3a shows, by way of example, two acceleration vectors a, representing the acceleration at two different times, for the measured acceleration vector from the calibration window. t1 and a t2 It is shown that:

[0043] The measured acceleration vectors from the offset window are averaged, thereby obtaining an offset vector a that eliminates the static influence of the rise / gradient or lateral gradient (track cant) of the track due to gravitational acceleration. o (See Figure 3a) is obtained. Next, this offset vector a o is subtracted from the measured acceleration vectors (a t1 and a t2 in Figure 3a), thereby obtaining the resulting acceleration vectors (a r1 and a r2 in Figure 3b). As a result, this acceleration vector corresponds only to the braking force in the longitudinal direction x Fahrzeug of the vehicle.

[0044] Figure 4 shows the same acceleration profile as Figure 2, but the profile shown in Figure 4 has been filtered by a low-pass filter and has already been offset-corrected by subtracting the offset sector. Furthermore, the fourth diagram no longer shows the acceleration profile in the z direction of the sensor as in Figure 2, but shows the angular profile, which will be discussed in more detail below. In these profiles, both the calibration window and the offset window are shown. Two time points t1 and t2 corresponding to the vectors in Figures 3a and 3b are shown as examples within the calibration window.

[0045] After the resulting acceleration vectors are formed within the calibration window, for each resulting acceleration vector a r (a r1 and a r2 in Figure 3b), an angle w r (w r1 and w r2 in Figure 3b) is determined. By this angle, the corresponding acceleration vector deviates from the x-axis of the sensor by which the longitudinal axis of the vehicle should be calibrated accordingly.

[0046] The profile of the angle w r over time is shown in the last diagram of Figure 4. As can be seen, the angle wr In the example shown, it takes a relatively small value. This is explained by the ratio of the measured acceleration in the x direction, which is high compared to the ratio in the y direction. All angles w obtained in this way within the calibration window r are averaged by forming the average value of w m to calculate the averaged angle w. By this much, the coordinate system of the sensor must be rotated about its z-axis (vertical axis), whereby the orientation of the x-axis of the sensor coincides with the longitudinal axis of the vehicle. By such rotation, the coordinate system of the sensor is calibrated to match the coordinate system of the vehicle.

[0047] FIG. 5 shows a flowchart for calibrating the x-axis of an acceleration sensor aligned with the longitudinal axis of a railway vehicle according to an embodiment of the present invention.

[0048] After the start of the x-axis calibration, which can be triggered by an operator or automatically by the system under set conditions, first, it is checked whether the preconditions for the x-axis calibration are met. These preconditions are, for example, whether the z-axis z of the sensor aligned with the vertical axis z Fahrzeug of the railway vehicle has already been calibrated, whether the speed v of the vehicle is higher than the required minimum speed v Sensor , or whether the target deceleration applied by the braking system exceeds the minimum target deceleration. If the preconditions are not met, this calibration is declared invalid and aborted. min If the preconditions are met, during low-speed driving, during the braking process to a stop state, on any route section, the acceleration progress is recorded by the acceleration sensor in all three coordinate directions. Subsequently, the measured acceleration progress is filtered, for example, by a low-pass filter, before checking whether the validity conditions of the measurement are met. Such conditions (post-conditions) are, for example, that braking to a stop state of the vehicle is necessary, and the measured acceleration vector a at each point

[0049] If the preconditions are met, during low-speed driving, during the braking process to a stop state, on any route section, the acceleration progress is recorded by the acceleration sensor in all three coordinate directions. Subsequently, the measured acceleration progress is filtered, for example, by a low-pass filter, before checking whether the validity conditions of the measurement are met. Such conditions (post-conditions) are, for example, that braking to a stop state of the vehicle is necessary, and the measured acceleration vector a at each point tThe value is the defined threshold a min , for example 0.5 m / s 2 is greater than, or in the stopped state, the measured acceleration value does not deviate from the gravitational acceleration by more than a defined value. If the post-condition is not met, this calibration is declared invalid and aborted.

[0050] If the post-condition is met, as described above, a calibration window and an offset window are defined, for example in relation to a stop jerk. In each window, acceleration vectors at various points in time are determined. These are each composed of the component in the x-direction and the component in the y-direction of the sensor. Subsequently, an offset vector is determined by averaging from the acceleration vectors within the offset window, which is then used for the correction of the acceleration vector a t from the calibration window. Thus, the resulting vector a r calculated in this way represents the deceleration of the vehicle in the longitudinal direction of the vehicle. In the next step, the angle w r between the x-axis of the sensor and the vector a r belonging to the resulting acceleration vector a r is calculated in the plane spanning the x-axis and the y-axis.

[0051] In the next step, it is checked whether the deviation between the angles w r1 resulting from two arbitrary resulting vectors a r2 and a r and the deviation of each vector value exceed the maximum allowable deviation, respectively. If the deviation exceeds the allowable range, this calibration is declared invalid and aborted.

[0052] If the deviation is within the allowable range, the resulting angle w r is averaged, thereby calculating the average angle w m . Finally, the coordinate system of the sensor is rotated by this angle, so that the x-axis x Sensor of the sensor has the same orientation as the longitudinal axis x Fahrzeug of the railway vehicle.

[0053] It should be noted that, without departing from the inventive concept of the independent claim related to the method, the measurement value recording of the acceleration process can also be executed during the acceleration process from a stopped state with appropriately adapted boundary conditions, rather than during the braking process to the stopped state.

Explanation of Reference Signs

[0054] 10 Train 20 Track 30 Sensor x Sensor Longitudinal direction of the sensor y Sensor Lateral direction of the sensor z Sensor Vertical direction of the sensor x Fahrzeug Longitudinal direction of the railway vehicle y Fahrzeug Lateral direction of the railway vehicle z Fahrzeug Vertical direction of the railway vehicle v Speed of the railway vehicle a x Acceleration in the longitudinal direction of the sensor a y Acceleration in the lateral direction of the sensor a z Acceleration in the vertical direction of the sensor t Time a t1 Acceleration vector at time t1 a r Resulting acceleration vector a o Offset vector w r Angle of the resulting acceleration vector w m Averaged angle

Claims

1. A method for calibrating the orientation of the longitudinal axis (x Ｓｅｎｓｏｒ ), and the transverse axis (y Ｓｅｎｓｏｒ ) of an acceleration sensor (30) mounted on a vehicle which is a railway vehicle, The acceleration sensor (30) has a coordinate system composed of the longitudinal axis (x Ｓｅｎｓｏｒ ), the transverse axis (y Ｓｅｎｓｏｒ ), and the vertical axis (z Ｓｅｎｓｏｒ ), and the axes are perpendicular to each other, The method comprises As step (A), over time, during the braking process of the vehicle (10) at a low speed, and further in a stopped state, along the longitudinal axis and the transverse axis (x Ｓｅｎｓｏｒ or y Ｓｅｎｓｏｒ ) of the sensor (30), measure the acceleration As step (B), a component in the direction of the longitudinal axis (x Ｓｅｎｓｏｒ ) and a component in the direction of the transverse axis (y Ｓｅｎｓｏｒ ) of the sensor, and an offset vector (a ｏ ) in a stopped state that represents the influence of gravitational acceleration on the measured acceleration of the vehicle is determined As step (C), at one point in time, from at least one measured acceleration vector (a Ｓｅｎｓｏｒ and y Ｓｅｎｓｏｒ ), which is composed of each measured acceleration in the directions of the longitudinal axis and the lateral axis (x ｔ ), subtract the offset vector (a ｏ ) to obtain at least one resulting acceleration vector (a ｒ ). As step (D), converting the coordinate system of the sensor so that the at least one resulting acceleration vector (a ｒ ) points in the longitudinal direction of the vehicle and has Before the step (A), align the vertical axis (z Ｓｅｎｓｏｒ ) of the sensor (30), which is perpendicular to the longitudinal axis (x Ｓｅｎｓｏｒ ) and the transverse axis (y Ｓｅｎｓｏｒ ) of the sensor, with the vertical axis (z Ｆａｈｒｚｅｕｇ ) of the vehicle for calibration. Ｓｅｎｓｏｒ ), with the vertical axis (z Ｓｅｎｓｏｒ ) of the sensor (30), which is perpendicular to the longitudinal axis (x Ｓｅｎｓｏｒ ) and the transverse axis (y Ｓｅｎｓｏｒ ) of the sensor, aligned with the vertical axis (z Ｆａｈｒｚｅｕｇ ) of the vehicle for calibration. Ｓｅｎｓｏｒ ), with the vertical axis (z Ｓｅｎｓｏｒ ) of the sensor (30), which is perpendicular to the longitudinal axis (x Ｓｅｎｓｏｒ ) and the transverse axis (y Ｓｅｎｓｏｒ ) of the sensor, aligned with the vertical axis (z Ｆａｈｒｚｅｕｇ ) of the vehicle for calibration. Ｓｅｎｓｏｒ ), with the vertical axis (z Ｓｅｎｓｏｒ ) of the sensor (30), which is perpendicular to the longitudinal axis (x Ｓｅｎｓｏｒ ) and the transverse axis (y Ｓｅｎｓｏｒ ) of the sensor, aligned with the vertical axis (z Ｆａｈｒｚｅｕｇ ) of the vehicle for calibration. Ｆａｈｒｚｅｕｇ ), with the vertical axis (z Ｓｅｎｓｏｒ ) of the sensor (30), which is perpendicular to the longitudinal axis (x Ｓｅｎｓｏｒ ) and the transverse axis (y Ｓｅｎｓｏｒ ) of the sensor, aligned with the vertical axis (z Ｆａｈｒｚｅｕｇ ) of the vehicle for calibration. In the stopped state of the vehicle (10), calibrate the vertical axis (z Ｓｅｎｓｏｒ ) of the sensor, and perform the calibration of the vertical axis (zSensor) of the sensor on the flattened measurement line. a method.

2. For the transformation of the coordinate system of the sensor in the step (D), the angle (w Ｓｅｎｓｏｒ between the longitudinal axis (x ｒ ) of the sensor and the at least one resulting acceleration vector (a ｒ ) is calculated in a plane spanning the longitudinal axis (x Ｓｅｎｓｏｒ ) and the transverse axis (y Ｓｅｎｓｏｒ ) of the sensor, and the coordinate system of the sensor is rotated by the calculated angle (w Ｓｅｎｓｏｒ ) about the already calibrated vertical axis (z ｒ ) of the sensor. The method according to claim 1.

3. To transform the coordinate system of the sensor (step (D)), a rotation matrix for rotation of the coordinate system of the sensor about the vertical axis (z Ｓｅｎｓｏｒ ), is determined, the rotation matrix being, here, in the directions of the longitudinal axis and the transverse axis of the sensor, of the at least one resulting acceleration vector (a ｒ ) to be determined unit vectors, the method according to claim 1.

4. The at least one resulting acceleration vector (a ｒ ) determined in said step (C) may be present within a calibration window having a temporally shiftable start and end and / or may be determined based on a parking jerk of said vehicle (10). The method according to any one of claims 1 to 3.

5. The method according to any one of claims 1 to 4, wherein, between the step (A) and the step (C), the measured acceleration history in the longitudinal and transverse directions of the sensor is filtered.

6. The method according to claim 5, wherein the measured acceleration history is filtered by a low-pass filter.

7. In the step (C), a plurality of resultant acceleration vectors (a ｒ ), are obtained, and then, angles (w ｒ ) corresponding to the obtained vectors are calculated respectively, and subsequently, the angles (w ｒ ) are averaged to obtain an averaged angle (w ｍ ). Next, rotate the coordinate system of the sensor by the calculated and averaged angle (w ｍ ), about the already calibrated vertical axis (z Ｓｅｎｓｏｒ ) of the sensor, the method according to any one of claims 1 to 6.

8. In the step (C), a plurality of resulting acceleration vectors (a ｒ ), are obtained, and then the acceleration vectors (a ｒ ) that are individually obtained as the result are averaged, The method according to any one of claims 1 to 7, wherein the transformation of the coordinate system of the sensor is performed based on the averaged acceleration vector resulting as the result, such that the acceleration vector resulting as the result points in the longitudinal direction of the vehicle.

9. The offset vector (a ｏ ) is determined by forming an average value of a plurality of detected acceleration vectors (a ｔ ) recorded within an arbitrarily defined offset window in the step (B), the method according to any one of claims 1 to 8.

10. The method according to claim 9, which cites claim 4, wherein the offset window is determined by the parking jerk of the vehicle.

11. Before the step (A), a condition, namely, whether the speed (v) of the vehicle exceeds a determined minimum speed (v ｍｉｎ ), and / or whether the target deceleration applied by the braking system of the vehicle exceeds a minimum target deceleration is inspected, and if one of the conditions is not satisfied, the calibration is not started. The method according to any one of claims 1 to 10.

12. After said step (A), a condition, namely that each measured acceleration vector (a ｔ ) has a magnitude exceeding a defined minimum acceleration (a ｍｉｎ ) up to near a standstill during said measurement, and / or that said braking process is carried out up to a standstill of the vehicle, and / or that the magnitude of the acceleration vector determined in said standstill deviates from gravitational acceleration by being below a defined magnitude, is checked, and if at least one of said conditions is not met, said calibration is not continued, the method according to any one of claims 1 to 11.

13. Before the step (D), the condition, i.e., that the magnitudes of the two resulting acceleration vectors (a ｒ１ ) and (a ｒ２ ) within the calibration window are different and below a defined magnitude, and if the condition is not met, not continuing the calibration, the method according to claim 4.

14. In the step (C), the angles (w ｒ１ ), and (w ｒ２ ) corresponding to the resulting acceleration vectors (a ｒ ) are calculated respectively, Before the step (D), conditions, i.e., the deviation between the said angles (w ｒ ) is checked to be less than a defined magnitude and different, and if the said conditions are not satisfied, the calibration is not continued, the method according to claim 13.

15. The recording of the acceleration along the longitudinal axis (x Ｓｅｎｓｏｒ ) and the transverse axis (y Ｓｅｎｓｏｒ ) of the sensor according to the said step (A), is also carried out during acceleration from a stationary state, the method according to any one of claims 1 to 14.

16. A method for constantly implementing the method according to any one of claims 1 to 15 during normal operation or implementing it at defined intervals.

17. An apparatus configured to implement the method according to claim 1, wherein the apparatus comprises an operation unit that is operated by an operator and is configured to receive commands from the operator, a storage unit configured to store data collected during the implementation of the method, a calculation unit configured to process data collected during the implementation of the method, and a data interface configured to receive data detected by a sensor and output data obtained and / or processed by the apparatus from the apparatus. An apparatus.

18. A computer program product configured to automatically execute all steps according to any one of claims 1 to 16.

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